Water-soluble pouches containing compositions are known in the art. For example, water-soluble pouches are used to package household care compositions including, but not limited to, laundry or dishwashing detergents or additives. A consumer can directly add the pouched composition to a mixing vessel, such as a bucket, sink or washing machine. Advantageously, this provides for accurate dosing while eliminating the need for the consumer to measure the composition.
Water-soluble pouches may contain compositions that comprise liquid including, but not limited to, water. The film materials used to make the water-soluble pouches are often permeable such that liquid contained within the pouch may migrate across the film. One such example of a common film material is polyvinyl alcohol (hereinafter “PVOH”).
Liquid migration from the composition contained inside the water-soluble pouch to the outside surface of the pouch is referred to herein as “weeping.” Weeping can lead to several undesirable outcomes. First, the outside surface of the pouch may become tacky. The tackiness can impede the flow of the water-soluble pouches along the pouch production line. For example, tacky pouches may stick together when flowing through the pouch counting and packing system. This can result in an inaccurate number of pouches being packed into a secondary container. Second, the weeping may cause the outside of the pouches to feel greasy to the touch.
Moisture from the air for example from ambient humidity may also cause the outside surface of the pouch to become tacky. This can also result in problems with sticky pouches and/or pouches that feel greasy to the touch.
One means of overcoming the aforementioned problems is to dust the outer surface of a water-soluble pouch with zeolite powder. In order to effectively coat the pouch, over-dried zeolite is preferred, due to its flow properties and its ability to effectively disperse and coat pouches. Without wishing to be bound by theory, it is believed that the structure of over-dried zeolite allows for capture of the liquid that is present on the surface of the film that is coated with the over-dried zeolite. While it is effective, over-dried zeolite can be difficult to manage due to its relatively short shelf life, its sensitivity to moisture pick up prior to use, the exothermic reaction when moisture or solvent enters the zeolite surface structures, and the expense to produce and supply such a sensitive material.
Regular zeolite (i.e., zeolite that has not been over-dried) can be a poor substitute for over-dried zeolite for a number of reasons. First, regular zeolite has a propensity for inconsistent flow through manufacturing processes. This can lead to poor dispersion and under or over coating of pouches. If undercoated, the pouches may have a tendency to display weeping. If overcoated, this can lead to pouches with a visible powder coating, resulting in a pouch appearance which may be unacceptable to consumers. When any zeolite is loaded with perfume or other actives, the flow properties of these powders are similarly poor and have the same issues when applied to coat pouches. Thus while zeolite will adequately perform as a coating in the present invention, over-dried zeolite will perform superiorly.
Thus there remains a need for a water-soluble pouch that is coated with a substance that will ameliorate the aforementioned problems. The substance should be delivered uniformly to the pouches and adhere consistently to the pouches, to allow for a relatively uniform distribution of powder on each pouch; this will result in a water-soluble pouch with desirable aesthetics.